Fabric coating containing energy absorbing phase change material and method of manufacturing same

ABSTRACT

A coating composition for fabrics includes wetted microspheres containing a phase change material dispersed throughout a polymer binder, a surfactant, a dispersant, an antifoam agent and a thickener. Preferred phase change materials include paraffinic hydrocarbons. The microspheres may be microencapsulated. To prepare the coating composition, microspheres containing phase change material are wetted and dispersed in a dispersion in a water solution containing a surfactant, a dispersant, an antifoam agent and a polymer mixture. The coating is then applied to a fabric.

This is a division of application Ser. No. 08/850,944 filed on May 5,1997 now U.S. Pat. No. 6,207,738 which is a continuation application ofprior application Ser. No. 08/259,964 filed on Jun. 14, 1994 abandoned.

FIELD OF THE INVENTION

This invention relates to substrate coatings containing energyabsorbing, temperature stabilizing phase change materials and methods ofmanufacturing same. More particularly, this invention relates to fabriccoatings containing microspheres of phase change material dispersed in apolymer binder and methods of manufacturing same.

BACKGROUND OF THE INVENTION

Coatings are typically applied to fabrics to increase water resistance,water transport, insulative ability or heat storage properties of thefabrics. Recently, microencapsulated phase change materials have beendescribed as a suitable component for fabric coatings when exceptionalheat transfer and storage capabilities are desired. In particular,International Patent Application No. PCT/93/05119 for “Fabric withReversible Enhanced Thermal Properties” to Colvin, et al., which isincorporated herein by reference, discloses that fabrics coated with abinder containing microcapsules filled with energy absorbing phasechange material enables the fabric to exhibit extended or enhanced heatretention or storage properties.

Research has demonstrated that applying a binder containing microspheresof phase change materials with commercial coating equipment can beproblematic. For example, use of solvent based gravure printingtechniques in which a solvent system was employed to achieve uniformdispersion of the microspheres in a binder proved unsuccessful becausethe solvent systems damaged the microspheres.

Thermoplastic gravure printing techniques also proved unsatisfactory foruse with microspheres of phase change material. When using highertemperature thermoplastic gravure printing techniques, sustainedtemperature of 325° F. caused severe damage to the microspheres.Although lower temperature thermoplastic gravure printing techniquesavoided significant damage to the microspheres, the resulting coatingwas found lacking in washability and durability. Moreover, lowertemperature thermoplastic gravure printing techniques precluded additionof the desired amounts of the microspheres, allowing addition ofmicrospheres of up to only about 20% by dry weight of themicrosphere/binder material. This low percentage of phase changematerial in the coating makes the coating susceptible to undesirableheat transfer across the coating, especially in locations where phasechange material is sparsely applied.

Attempts to encapsulate microspheres of phase change materials in athermoplastic spray have also proved unsatisfactory. In particular,scattering microspheres into a stream of sprayed, fibrous thermoplasticmaterial resulted in a binder matrix that did not fully encase themicrospheres. The resulting binder/microsphere material was susceptibleto loss of microspheres, which worked loose and were continually sheddedfrom the fabric. In addition, the coating lacked uniformity of thicknessand microsphere distribution.

Attempts were also made to utilize thermoplastic extrusion techniques tocreate a film of continuous web in which microspheres of phase changematerial were uniformly distributed. However, thermal breakdown of themicrospheres resulted from the higher temperatures utilized. Theextrusion screw employed with these techniques also physically damagedthe microspheres.

Phase change materials in microencapsulated form are commonly suppliedas a dry powder. This powder is difficult to wet and uniformly dispersein aqueous systems. Moreover, some microencapsulated phase changematerials have an internal layer of modified gelatin which ishydrophilic and capable of absorbing its own weight in water. Not onlydoes the hydrophilic quality of such microcapsules make more standardcomponent proportions inapplicable, microcapsules which have absorbedwater tend to swell and associate, increasing the viscosity of thecoating system above acceptable limits. Although the precise behavior ofmicrocapsules in the coating system which have absorbed water isuncertain, it is believed that such microcapsules agglomerate, reducingtheir dispersion throughout the binder of the coating system, whichde-stabilizes the binder. This de-stabilization can increase over time.When latex binders are used with microencapsulated phase changematerial, de-stabilization of the latex binder can continue until thelatex binder coagulates.

U.S. Pat. Nos. 5,254,380, 5,211,949, 5,282,994 and 5,106,520 for “DryPowder Mixes Comprising Phase Change Materials” describe free flowing,conformable powder-like mixes of silica particles and a phase changematerial which the silica particles of between 7×10⁻³ to 7×10⁻² micronsare mixed with phase change material in a ratio of up to 80% by weightof phase change material. While these patents describe a matrix in whichmicrospheres of phase change materials need not be separatelyencapsulated, they do not describe the use of dry powder mixescontaining phase change materials in binder matrices for coatingfabrics.

It is against this background that the significant improvements andadvancement of the present invention have taken place in the field offabric coatings containing energy absorbing, temperature stabilizingphase change materials and methods of manufacturing same.

OBJECTS OF THE INVENTION

It is the principal object of the present invention to provide animproved fabric coating composition containing phase change material ofa density sufficient to effect or control heat and energy transferacross the coating and/or store heat in the coating.

It is another object of the present invention to provide a coatingcomposition of the foregoing character which will maintain substantiallyall of the breathability, flexibility or other principal qualities ofthe fabric to which it is applied.

It is a further object of the present invention to provide coatedfabrics having the aforementioned properties which are resistant toheat, pressure and chemicals encountered during the coating process.

It is a still further object of the present invention to provide coatedfabrics having the aforementioned qualities which are durable, resistantto heat, moisture, solvents, laundering, and/or drycleaning, withoutdegradation to or loss of the phase change material.

It is still another object of the present invention to provide animproved method of applying coating compositions containing phase changematerials and having the aforementioned qualities as coatings on fabricsby utilizing commercially available equipment.

It is yet another object of the present invention to provide an improvedmethod of applying coatings containing phase change materials to fabricswithout damage or degradation to the phase change materials.

It is still another object of the present invention to provide animproved method for evenly dispersing phase change material throughout abinder and maintaining an even distribution of the phase change materialwhile coating a fabric with the binder and phase change materialdispersion.

SUMMARY OF THE INVENTION

The present invention comprises coatings for fabrics and methods formanufacturing the same. A preferred coating includes wetted microspherescontaining a phase change material dispersed throughout a polymer latexbinder, and including a surfactant, a dispersant, an antifoam agent anda thickener. Preferred phase change materials include paraffinichydrocarbons. To prepare a preferred coating composition of the presentinvention, microspheres containing phase change material are dispersedin an aqueous solution of a surfactant, a dispersant, and an antifoamagent mixture, followed by dispersion in a polymer mixture to form acoating composition. An alternative method of preparing the coatingcomposition of the present invention includes dispersing microspherescontaining phase change material in wet cake form in an aqueous solutionof a surfactant, a dispersant, antifoam agent and polymer to form acoating composition. The coating composition of the present inventionare then applied as a coating on a fabric.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present application, it has been discovered thatwetting microspheres of phase change materials with water andmaintaining a uniform dispersion of the microcapsules in a wet coatingminimizes or eliminates the tendency of such microspheres to destabilizethe binder polymer in which the microspheres are dispersed.

A coating composition which includes microspheres containing a phasechange material is prepared by mixing dry microspheres with an excess ofwater to induce the microspheres to swell with water until swelling iscomplete. Preferably, a surfactant and a dispersant are added to thewater prior to mixing with the microspheres. The surfactant decreasessurface tension of the layers of the microspheres and thereby promoteswetting of the microspheres. An antifoam agent is added to and mixedslowly with the microsphere/water mixture to remove air trapped asdispersed bubbles in the mixture. A thickener is added to adjust theviscosity of the mixture to prevent the microspheres from floating orsinking in the mixture. A viscosity of at least 500 cps is preferred.Adjusting the pH of the mixture to 8.5 or greater promotes swelling ofthe microspheres. Swelling is typically complete in from 6 to 24 hours,at which time the microspheres will have reached an equilibrium with theaqueous phase in which they are dispersed. Thereafter, the microspheredispersion is added to a mixture of a polymer dispersion, surfactant anddispersant having a pH approximately the same as the pH of themicrosphere dispersion. The viscosity and rheology of the resultingcoating compound is adjusted to meet the requirements of the coatingmethod employed.

The polymeric binder may be in the form of a solution, dispersion oremulsion in water or in organic solvent. The polymeric binder mayinitially be polymeric, or in the form of monomers and/or oligomers, orlow molecular weight polymers which upon drying and/or curing areconverted to their final molecular weight and structure. These bindersare preferably film-forming, elastomeric, and have a glass transitiontemperature in the range of about −45° C. to +45° C., depending upon thedesired application. For most garment applications, an elastomericpolymer with a glass transition temperature of about −30° C. to about+12° C. is preferred.

The polymers may be linear or branched. Copolymers may be random, blockor radial. The polymers may have pendant reactive groups, reactive endsor other crosslinking mechanisms, or be capable of entanglement and/orhydrogen bonding in order to increase the toughness of the finishedcoating and/or its resistance to heat, moisture, solvents, laundering,dry-cleaning or other chemicals.

Suitable monomers include, but are not limited to, acrylic eaters(preferably alkylacrylates and methacrylates containing 4 to 17 carbonatoms); styrene; isoprene; acrylonitrile; butadiene; vinyl acetate;vinyl chloride; vinyldiene chloride; ethylene; butylene; propylene;chloroprene; etc. Polymers and copolymers based upon the above mentionedmonomers and/or upon silicone; epoxy; polyurethane; fluorocarbons;chlorosulfonated polyethylene; chlorinated polyethylene; and otherhalogenated polyolefins are also useful.

The surfactant described above has a preferred wetting time of notgreater than 50 seconds at a concentration of 0.10 % by the DravesWetting Test. Nonionic and anionic surfactants are acceptable. Dioctylsodium sulfosuccinamate (sometimes referred to herein as “DOS”) is apreferred surfactant.

The dispersing agent employed as described above is preferably anonionic or anionic dispersant, such as dispersants based upon phosphateesters. A 90% solution of the potassium salt of a phosphated coester ofan alcohol and an aliphatic ethoxylate such as Strodex PK907 availablefrom Dexter Chemical Company of New York City, N.Y. is a preferreddispersant.

From 0.1% to 0.8% by weight of dry DOS to dry microspheres and from 0.1%to 0.8% by weight of dry PK90™ to dry microspheres is effective. Thetotal amount of DOS and PK90™ is preferably apportioned equally betweenthe dry microsphere dispersion and the polymer dispersion to which themicrospheres will be added after swelling is complete.

Suitable thickeners include polyacrylic acid, cellulose esters and theirderivative, polyvinyl alcohols, and others known in the art. A preferredthickener is Acrysol ASE60™ available from Rohm and Haas Company ofPhiladelphia, Pa. ASE60™ is preferably obtained as a 28% solution of analkali-swellable polyacrylic acid which increases in viscosity uponneutralization. As described above, thickener is added first to achievethe desired viscosity of the microsphere dispersion, which will varydepending on the particular phase change material selected, and then toadjust the wet coating to meat the requirements of the coating methodemployed.

Preferred antifoam agents include aqueous dispersions of silicone oil,such as polydimethylsiloxane, containing dispersed fine particle silica,and mixtures of mineral oil, surfactant and fine particle silica, suchas AF 9020™ available from General Electric Company of Waterford, N.Y.,and Advantage 831™ available from Hercules Chemical Company ofWilmington, Del.

A preferred polymer binder is made with a dispersed polymer latex is ananionic, heat reactive, acrylic latex containing 59% non-volatiles inwater, such as the acrylic polymer latex marketed under the tradenameHycar XT9202™ and available from B. F. Goodrich Chemical Company ofCleveland, Ohio. The polymer latex has a glass transition temperature of−25° C. When properly dried and cured, fabric coatings made from polymerlatex such as Hycar XT9202™ are washable and dry-cleanable.

The coating compositions of the present invention preferably includefrom 30 to 500 parts by dry weight of microspheres for each 100 parts bydry weight of acrylic polymer latex. The coating compositions preferablyinclude from 0.005% to 6% dry weight each of surfactant and dispersantto dry weight of microspheres. Water is added to total 25% to 80% of thefinal wet coating composition. An antifoam agent of from 0% to 1% dryweight to total weight of the final wet coating composition ispreferred. The most preferred ratios of components of the coatingcomposition of the present invention are: 70 to 300 parts by dry weightof microspheres for each 100 parts by dry weight of acrylic polymerlatex, 0.1% to 1% dry weight each of surfactant and dispersant to dryweight of microspheres, water totaling 40% to 60% of the final wetcoating composition and antifoam agent of from 0.1% to 0.5% dry weightto total weight of the final wet coating composition.

An alternative method utilizes microspheres of phase change materialwhich are not completely dried during the manufacturing process. Wetmicrospheres containing from about 25% to about 65% by weight water arepreferred and can be readily handled. When using such microspheres, asurfactant and a dispersant are added to a polymer binder dispersionbefore the wetted microspheres are dispersed therein. DOS and StrodexPK90™ are preferably mixed with the polymer binder dispersion before thewet microspheres are mixed with and dispersed therein.

Generally speaking, phase change materials have the capability ofabsorbing or releasing thermal energy to reduce or eliminate heattransfer at the temperature stabilizing range of the particulartemperature stabilizing material. The phase change material inhibits orstop the flow of thermal energy through the coating during the time thephase change material is absorbing or releasing heat, typically duringthe material's change of phase. This action is transient, i.e., it willbe effective as a barrier to thermal energy until the total latent heatof the temperature stabilizing material is absorbed or released duringthe heating or cooling process. Thermal energy may be stored or removedfrom the phase change material, and can effectively be recharged by asource of heat or cold. By selecting an appropriate phase changematerial, a fabric can be coated for use in a particular applicationwhere the stabilization of temperatures is desired. Two or moredifferent phase change materials can be used to address particulartemperature ranges and such materials can be mixed.

Paraffinic hydrocarbon phase change materials suitable for incorporationinto fabric coatings are shown below in Table I. The number of carbonatoms contained in such materials and is directly related to the meltingpoint of such materials.

TABLE I COMPOUND NO. CARBON ATOMS MELTING POINT ° C. n-Octacosane 2861.4 n-Heptacosane 27 59.0 n-Hexacosane 26 56.4 n-Pentacosane 25 53.7n-Tetracosane 24 50.9 n-Tricosane 23 47.6 n-Docosane 22 44.4n-Henelcosane 21 40.5 n-Elcosane 20 36.8 n-Nonadecane 19 32.1n-Octadecane 18 28.2 n-Heptadecane 17 22.0 n-Hexadecane 16 18.2n-Pentadecane 15 10.0 n-Tetradecane 14 5.9 n-Tridecane 13 −5.5

Phase change materials such as the listed paraffinic hydrocarbons arepreferably formed into microspheres and encapsulated in a single ormulti-layer shell of gelatin or other materials. Encapsulatedmicrosphere diameters of from 1 to 100 microns are preferred, mostpreferably in the range 10 to 60 microns. Encapsulated microspherescontaining phase change materials are sometimes referred to herein as“microPCMs.” Microspheres may also be bound in a silica matrix ofsub-micron diameters. Microspheres containing n-octadecane or n-eicosaneare suitable for fabric coatings for clothing. Such microspheres areavailable from MacGill Enterprises, Inc. of West Milton, Ohio andMicrotek Laboratories, Inc. of Dayton, Ohio.

EXAMPLE I

A preferred coating formulation where high phase change material contentand limited extensibility is required, for example with non- orlow-stretch fabrics such as non-woven or woven fabrics, is prepared asshown in Table II.

TABLE II COMPONENT WT % DIRECTIONS MICROSPHERE DISPERSION: Water 35.0075% DOS 0.40 Strodex PK90 (90% NV) 0.20 n-Elcosane microspheres (dry)36.50 Acrysol ASE60 (28% NV) 1.00 Mix, dispersing ingredients well.AF9020 (20% NV) 0.05 Mix slowly with dispensed ingredients until foamdissipates. Ammonium hydroxide (28%) 0.50 Add slowly to the defoameddispersion, with good mixing. Let stand 6 hours. Remix immediatelybefore use. POLYMER BINDER DISPERSION: Hycar XT9202 latex polymer 21.3575% DOS 0.20 Strodex PK90 0.10 Acrysol ASE60 (26% NV) 3.40 HerculesAdvantage 831 0.30 Mix ingredients slowly until foam dissipates.COATING: Ammonium Hydroxide 1.00 Slowly add Microsphere Dispersion toPolymer Binder Dispersion; add ammonium hydroxide slowly with goodmixing thereto.

EXAMPLE II

An alternative coating formulation where high phase change materialcontent and limited extensibility is required, for example with non- orlow-stretch fabrics such as non-woven or woven fabrics, is prepared asshown in Table III.

TABLE III COMPONENT WT % DIRECTIONS Hycar XT9202 21.00 75% DOS 0.40Strodex PK90 (90% NV) 0.33 Mix. 50% wet n-Octadecane 72.00 Add slowly tolatex polymer microspheres mixture, with good mixing, dis- persingmicrospheres well. Acrysol ASE60 (28% NV) 4.40 AF9020 (20% NV) 0.05Hercules Advantage 831 0.30 Mix ingredients slowly until foamdissipates. Ammonium Hydroxide (28%) 1.52 Add slowly, with good mixing.

Addition of microspheres as described above in the preferred weightratios eliminates tack and prevents blocking of the coated fabricstypically experienced with coatings having low glass transitiontemperature polymers such as those based on acrylic latex polymers.Tack, the tendency of material to stick to itself, can make rolls ofcoated fabric difficult to unroll. This can occur when rolls of coatedfabric are stored in warm places or are stored under pressure of rollsstacked on top of one another. Antiblocking additives are typicallyadded to coating formulations to prevent tack. The presence ofmicrospheres in the coatings of the present invention eliminates theneed for antiblocking additives.

Non-foam coating compositions like those described in Examples I and IIabove are suitable for application to substantially non-extensiblefabrics of both woven and non-woven construction. A preferred coatedfabric is produced using the non-foam coating like that of Example I anda 100% polyester, non-woven fabric having a weight of 0.8 oz/sq yd. Apreferred fabric selected is HEF™ (a hydro-entangled fiber) obtainedfrom Veretec™ of Bethune, S.C. Similar fabrics are available from duPont de Nemours Company. Using a wet coating composition containing 50%by dry weight of microspheres, a knife-over-roll coating headconfiguration is employed. A desired weight of 2.5 oz dry weight ofmicrospheres/sq yd is obtained with a knive-over roll gap of 0.022inches off the fabric. The coating line speed is 8 linear yards perminute. The coating is cured at a temperature of approximately 260° F.

EXAMPLE III

A preferred foam coating formulation of the present invention may beused with breathable fabric to maintain the heat and moisturedissipation capability of the fabric. In this example, the materials aresubject to mechanical frothing. Foam stabilizers are added to maintainthe foam after application to the fabric. Foam stabilizers may beinorganic salts of fatty acids or their sulfate partial esters, anionicsurfactants, among other compounds. Preferred foam stabilizers for usewith phase change material microspheres are sodium lauryl sulfate,ammonium stearate, di-sodium-n-octadecyl sulfosuccinamate and mixturesthereof. Ammonium stearate concentrations (dry as a percent of wetcoating) of 0.5% to 6% plus 0.2% to 4% sulfosuccinamate are mostpreferred. The coatings are prepared as shown in Table IV.

TABLE IV COMPONENT WT % DIRECTIONS Water 4.69 75% DOS 0.20 Strodex PK90(90% NV) 0.17 Hycar XT9202 33.74 35% wet n-Octadecane 54.53 Add slowlyto above ingredients, microspheres dispersing microspheres well. AF9020(20% NV) 0.05 Mix slowly, until foam dissipates. Acrysol ASE60 (20% NV)1.55 Hercules Advantage 831 0.23 Mix ingredients slowly until (28% NV)foam dissipates. Ammonium Hydroxide (28%) 0.60 Add slowly while mixing.Do not mix in air. Ammonium Steaerate (33%) 2.96 Di-sodium-n-octadecyl-1.28 Add slowly, with good mixing. sulfosuccinamate (35%)

Preferred foam coatings contain ammonium stearate in an amount by dryweight of from 0.25% to 10% of the total weight of the final wet coatingcomposition foam is preferred and from 0.1 to 8% dry weight ofsulfosuccinamate to total weight of the final wet coating compositionfoam. Most preferably, ammonium stearate by dry weight 1% to 3% of thetotal weight of the final wet coating composition foam and thesulfosuccinamate by dry weight comprises from 0.3 to 2% dry weight tototal weight of the final wet coating composition foam.

The liquid coating is mechanically foamed by pumping through an Oakesmixer or similar mechanical foamer. The mixer injects air into theliquid and finely disperse the air. The foamed liquid is pumped to acoating head, usually a knife coater, where it is spread onto thefabric. The fabric/foam coating is then passed through a heated oven todry and cure the foam.

Foam coating compositions like those described in Example III are alsosuitable for application to substantially non-extensible fabrics of bothwoven and non-woven construction when maintaining breathability of thefabric is desired. A preferred methodology includes applying the foamcoating of Example III to HEF™ having a weight of 1¼ oz/sq yd. The wetcoating composition of Example III is foamed to a preferred blow ratioof air to wet compound of 2:1, with acceptable blow ratios ranging from½:1 to 10:1. A knife-over-roll coating head configuration is employed.The desired weight of 0.5 oz dry weight of microspheres/sq yd isobtained with a knive-over roll gap of 0.018 inches off the fabric. Thefabric is drawn through the coating line at a rate of 10 linear yardsper minute. The coating is cured at a temperature of approximately 260°F., with the fabric carried on a tenter frame to prevent shrinkage ofthe fabric.

EXAMPLE IV

Tests were conducted on acrylic fleeces in which the fibers containingmicroPCMs, and on non-woven materials (sometimes referred to herein asA“substrate”) having a coating containing microPcMs. Acrylic fleeceswithout microPCMs having approximately the same weight per unit area asthe fleeces with microPCMs, and substrates without microPCMs having thesame thickness as the non-woven substrates having a coating containingmicroPCMs, served as comparison materials. Specific data regarding thesample materials tested are included in Table V.

TABLE V Acrylic Substrate Acrylic without Substrate without MaterialsTested with PCM PCM with PCM PCM Wt/unit area (g/m²) 270 250 227 207Stand thickness (mm) 5.40 5.63 0.63 0.61 Compressibility (lbs) 12 16 1320 Raw density (kg/m³) 49 44 360 339

The content of microPCMs in the acrylic fleeces was approximately 10 percent. About 7 g/m² microPCM was included in the coating of the non-wovensubstrate. This is equal to a content of microPCM of about 3%. The phasechange temperature of the microPCM material ranged from about 22° C. toabout 25° C.

Tests of water-vapor permeability and water-vapor absorption of thematerials were based upon the test methods of the standards DIN 53 332and DIN 53 333. The tests of the water-vapor permeability were carriedout under constant climatic conditions of 23° C. temperature and 40%relative humidity. The water-vapor absorption of the materials wastested at a constant environmental temperature of 23° C. at varyingrelative humidities. The following thermophysical parameters of thematerials were measured: thermal conductivity (A); thermal resistance(R); temperature conductivity (a); and specific thermal capacity (c).

Test results indicated that the water-vapor permeability is notinfluenced by the incorporation of microPCMs. The acrylic fleeces testedpossess a water-vapor permeability of about 5 mg/cm²/h as a result ofthe material structure. The non-woven substrate to which the microPCMlayer is applied is with about 0.75 mg/cm²/h, nearly impermeable forwater-vapor.

The water-vapor absorption of the samples is primarily determined by theabsorption ability of the basic material. The incorporated microPCMcauses a slight increase of the water-vapor absorption under the sameclimatic conditions. The water-vapor absorption of the acrylic fleecewithout microPCM was about 1.5% at a temperature of 23° C. and arelative humidity of 80%. The acrylic fleece with microPCM absorbs about0.3% more water-vapor under the same conditions.

Tests of heat insulation and the heat storage were carried out undervarying temperature, humidity and static pressure. Test conditions witha material temperature in the phase change range of 24° C., a materialhumidity that results from 30% air humidity and a pressure of 1 kPa wereselected as a starting point for the measurements. Table VI is a summaryof the test results.

TABLE VI thermophysical Acrylic Acrylic Substrate Substrate parameterswith PCM without PCM with PCM without PCM A (w/m K) 0.0398 0.0342 0.10120.1782 R (m² K/W) 0.1281 0.1491 0.0057 0.0029 c (kJ/kg K) 3.022 2.3912.468 1.840

As shown above in Table VI, materials with incorporated microPCM possessan essentially higher heat storage than the comparison material. Theheat insulation of the compact non-woven substrate is enhanced by themicroPCM coating. The heat insulation of the acrylic fleece is mainlydetermined by the air enclosed in the material as a result of thedispersed structure of the fabric.

It has been determined that the heat insulation properties of thematerials containing microPCM remain nearly constant in the temperaturerange of the specific phase change, in contrast to the behavior ofmaterials which do not contain microPCM. The variation of the heatinsulation of the materials with microPCM is essentially lower contraryto the comparison material in changes of material humidity. Thematerials with microPCM possess when raising the pressure on the textilea lower decrease in the heat insulation than the comparison material dueto a lower compressibility of the materials with microPCM.

To determine the protection effect of the samples, the samples werebrought in contract with a 70° C. tempered plate after cooling under thephase change temperature. The time required to reach a temperatureequivalent to the pain threshold of the human skin on back of the samplewas determined. The higher protection effect for the materials withmicroPCM was confirmed.

Presently preferred embodiments of the present invention and many of itsimprovements have been described with a degree of particularity. Itshould be understood that this description has been made by way ofpreferred examples, and that the invention is defined by the scope ofthe following claims.

What is claimed is:
 1. A method of manufacturing a coating compositionfor use in coating a fabric comprising the steps of: mixing water, asurfactant, a dispersant, microspheres containing a phase changematerial, and a thickener to produce a mixture; dispersing saidmicrospheres throughout said mixture to produce a first dispersion;adding an antifoam agent to said first dispersion to dissipate foam fromsaid first dispersion; mixing a polymer latex, a surfactant, adispersant, a thickener and an antifoam agent to form a seconddispersion; and mixing said second dispersion with said first dispersionto produce said coating composition.
 2. The method of claim 1 furthercomprising the steps of: adding a base to said first dispersion prior tomixing said first with said second dispersion; and adding a base to saidcoating composition after mixing said first with said second dispersion.3. The method of claim 1 further comprising the step of: maintaining auniform dispersion of said microspheres in said first dispersion forfrom 1 to 48 hours prior to mixing said second dispersion with saidfirst dispersion to produce said coating composition.
 4. The method ofclaim 1 further comprising the step of: maintaining a uniform dispersionof said microspheres in said first dispersion for from 6 to 24 hoursprior to mixing said second dispersion with said first dispersion toproduce said coating composition.
 5. A method of manufacturing a coatingcomposition comprising the steps of: mixing a polymer latex, asurfactant and a dispersant to obtain a first mixture; adding wetmicrospheres that contain at least 25% by weight of water and a phasechange material to the first mixture to obtain a second mixture;dispersing the wet microspheres throughout the second mixture to obtaina dispersion; mixing the dispersion with an antifoam agent and athickener to form a third mixture that is defoamed and thickened; andadding a base to the third mixture to create said coating composition.